1. Field of the Invention
This invention pertains to a method of improving reservoir sweep efficiency in secondary and tertiary oil recovery operations.
2. Description of the Prior Art
In secondary and tertiary operations, the ultimate recovery is strongly affected by the sweep efficiency in the reservoir. Poor vertical sweep results not only in reduced recovery but in higher operating costs due to cycling of injected fluids. Many different procedures have been attempted to improve vertical sweep. A major problem encountered in previous efforts is the problem of selectively placing a plugging agent in so-called thief zones in the formation to divert the flow of treatment fluids to less permeable portions of the formation. This invention is a procedure which can improve the operator's ability to selectively place the plugging agent.